1. Field of the Invention
The present invention relates to a bus driver for a data processing system.
2. Description of the Related Art
In a data processing system, a plurality of packages each including a semiconductor integrated circuit are inserted into a back panel. The packages share buses formed on the back panel. In this case, each of the packages has a bus driver and a bus receiver.
A prior art bus driver includes an open drain type metal oxide semiconductor (MOS, broadly, metal insulating semiconductor (MIS)). This will be explained later in detail.
However, the prior art bus driver per se does not include a noise removing circuit, so that a large ringing effect is generated in the bus. Therefore, it takes a long time to converge the ringing effect, which substantially increases the propagation delay time of signals from the bus driver to its respective bus receivers. Also, it is difficult to increase the frequency of the propagated signals.
It is an object of the present invention to reduce the ringing effect in a bus driver, thus substantially reducing the signal propagation delay time as well as increasing the frequency of the propagated signals.
According to the present invention, in a bus driver for driving a bus having first and second power supply terminals, an input terminal for receiving an input signal and an output terminal connected to the bus, a switching element is provided between the output terminal and the second power supply terminal, and the switching element is controlled by a voltage at the input terminal. A pull-up resistor is connected between the first power supply terminal and the output terminal.